Fangs and Heavy Metal: A Bioaccumulation Study
Featured Image Caption: South American Rattlesnake (Crotalus durissus) by Holger Krisp CC by 3.0 via Wikimedia Commons
Primary Source Article: Toledo, F.A.d.O., Santos, D.O., Vasconcelos, I.M.A. et al. Heavy metals bioaccumulation in free-ranging South American rattlesnakes (Crotalus durissus) in Southeastern Brazil. Environ Sci Pollut Res 31, 32339–32349 (2024). https://doi.org/10.1007/s11356-024-33432-5
Secondary Source Article(s): Tasima, L. J., Lima, E. O. V. de, Hatakeyama, D. M., Vidueiros, J. P., Stuginski, D. R., Grego, K. F., & Tanaka-Azevedo, A. M. (2024). Seasonality in Crotalus durissus venom. Toxicon (Oxford), 244, 107748–107748. https://doi.org/10.1016/j.toxicon.2024.107748
Fernandes-Filho, E. I., Reynaud Schaefer, C. E. G., Faria, R. M., Lopes, A., Francelino, M. R., & Gomes, L. C. (2022). The unique and endangered Campo Rupestre vegetation and protected areas in the Iron Quadrangle, Minas Gerais, Brazil. Journal for Nature Conservation, 66, 126131-. https://doi.org/10.1016/j.jnc.2022.126131
Campolina, D., Ciminelli, V.S.T., Ng, J.C. et al. Speciated and Total Urinary Arsenic Levels in Belo Horizonte, the Largest Brazilian City within the Mineral-Rich Region “Iron Quadrangle”. Expo Health16, 101–118 (2024). https://doi.org/10.1007/s12403-023-00540-5
“You have heavy metal in your blood”-unless someone is referring to rock music, this is a statement no one wants to hear from a health professional. Unfortunately, human activities can affect urban and wildlife environments. Heavy metals such as cadmium, copper, magnesium, lead, and zinc enter the environment through agricultural runoff, waste management, and industrial activities such as mining and smelting. Once these metals contaminate the soil and water, they make their way up the food chain and build in an organism over time in a process called bioaccumulation. Bioaccumulation has been documented in plants, birds, mammals, amphibians, and fish. However, Toledo and colleagues are the first to document bioaccumulation in rattlesnakes in Southeastern Brazil. Through biochemical analysis of blood, liver, and kidneys, scientists discovered that rattlesnakes had high concentrations of heavy metals that differed depending on the different regions studied in Brazil. Studying the bioaccumulation of toxic and essential metals in free ranging rattlesnakes could be used for future studies in determining the extent of pollution in an environment.
Snake Handling For Science
“Crotalus durissus” by Salomão Janderson Ferreira Bispo, CC By 4.0 via Wikimedia Commons
Rattlesnakes belong to the genus Crotalus and are found in the Americas, from southern Canada to northern Argentina. In Brazil, snake bite cases are often caused by rattlesnakes. Being bitten by a venomous snake can cause breakdown of muscle, renal failure, neurotoxicity, paralysis, and death, if untreated. These animals are about 1.5 meters long and can live for 15 years, which makes them valuable for studying bioaccumulation. In this study, the rattlesnakes were collected from a region in Brazil known for heavy mining activity.
The study focused on studying toxic and essential metals in the blood and organs of 96 free-ranging rattlesnakes (Crotalus durissus) from Minas Gerais, Brazil. Information such as sex, body weight, and blood samples were taken before the snakes were humanely euthanized to collect liver and kidney samples. Scientists focused on measuring cadmium, lead, chromium, arsenic and essential metals magnesium, zinc, and copper.
Metals Provide Clues About Human Activity
All of the rattlesnakes that were studied had varying levels of metal and essential mineral accumulation. These results could be explained by the behavior of the metals and the human activity that was associated with the different areas studied in Southeastern Brazil. Bioaccumulation was highest in heavier males. Heavier organisms tend to accumulate more environmental contaminants. Overall, these substances accumulate in the kidney, liver, and bone. Blood tests revealed that arsenic, magnesium, and lead affected blood cell count, but blood cells may also have been partially affected by infectious and parasitic diseases. Snakes with higher levels of zinc and magnesium came from the region “Oeste de Minas Gerais”, an area known for mining and agriculture. Soils contaminated with lead are associated with highways. In addition arsenic was detected in some, but not all of the snakes. This could be explained by being near areas of burning fossil fuels, metal casting, semiconductor and glass industries, or materials with herbicides and fertilizers.
This study and many like it will provide important reference data for determining the extent of environmental pollution. For example, a bioaccumulation approach can be used to determine whether an environmental regulation focusing on reducing pollution actually generates a meaningful impact in an area. This bioaccumulation study provides a clear picture of the environmental contamination in the study area, setting the stage for future work monitoring metal pollution using wildlife.
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